How many voters should be sampled such that the sampled fraction of voters favoring the bond issue will between 0.15 and 0.35 with probability at least 0.96?

A pollster believes that 25% of the voters in a certain area favor a bond issue. a) Suppose that n = 200 voters are randomly sampled from the large number of voters in this area, what is the probability that at most 60 voters favor the bond issue?

b) How many voters should be sampled such that the sampled fraction of voters favoring the bond issue will between 0.15 and 0.35 with probability at least 0.96?

Find the sample size n by using (i) the Chebyshev inequality and (ii) the normal approximation.